Can I remove an EFI partition and join the space with Macintosh HD?

Let me tell you the story to understand the problem. I installed Ubuntu 20.04 on my mac as the second OS. Later I decided to delete it, and being not good in all this stuff, I decided to just remove the 30gb partition I gave for Ubuntu. However, EFI partition was left. I downloaded Paragon and erased this EFI. But it is not merged still with my Macintosh HD. I tried to format it as HFS+ and then tried to make it APFS but my system felt and I had to install macOS again. Disk Utility says that there is a trouble and to repair it, I need to go to recovery mode. But when I go to RM, it says the same thing - even though I turned off filevault as some sources say. So my question is how to merge it (include literally the 314.57 Mb partition) with my hard disk (APFS-container)?